| With the development of portable electronic products,electric vehicles and hybrid electric vehicles,reversible electrochemical energy storage devices have received much attention in recent years.So far,lithium-ion batteries?LIBs?have dominated power supplies in countless applications due to their high theoretical capacity,high energy density,and low cost.However,the theoretical capacity of LIBs for commercial graphite anodes is limited to372 mA h g-1,making it difficult to meet the challenging requirements of fast-growing markets.In order to improve the energy density of LIBs,the pursuit of advanced anode materials with higher specific capacity is necessary.In the past few decades,due to the high theoretical capacity of transition metal oxides,moderate volume expansion and low cost properties,widespread attention has been paid.MnO is a promising high-capacity anode material for LIBs,but the raw materials have short cycle life and poor rate capability,thus hindering practical applications.In addition,with the wide application of LIBs,the safety of batteries has also received attention from all walks of life.Solid-state lithium metal batteries have become a promising alternative to liquid LIBs,and offer higher energy output and better safety to power the future storage market.Among various solid electrolytes,polymer electrolytes have attracted much attention due to their potential advantages,including a wide electrochemical window,ease of processing,low interface impedance,and low cost.Polymer electrolytes based on poly?ethylene oxide??PEO?as a well-known polymer matrix have been extensively studied because their highly flexible EO segments in the amorphous phase can provide channels for lithium ion transport.However,obtaining a PEO-based solid electrolyte with high Li ion conductivity without sacrificing mechanical strength remains a significant challenge.This paper is mainly devoted to the preparation of three-dimensional porous LIB anode materials and the design of all solid-state batteries.The specific work is as follows:1.A novel porous MnO microsphere was prepared by a simple self-template method.The microspheres were connected by nitrogen-doped porous carbon?3DHB-MnO@NC?and have a well-connected hierarchical three-dimensional network structure.The 3DHB-MnO@NC electrode can effectively promote ion/electron transfer and buffer the large volume change of the electrode during the electrochemical reaction.As the negative electrode of LIBs,3DHB-MnO@NC has excellent cycle performance(1247.7 mA h g-1 after 90 cycles at 200mA g-1)and good rate performance(949.6 mA h g-1after 450 cycles at 1000 mA g-1).2.In this study,polymethylhydrogensiloxane?PMHS?with low glass transition temperature and good flexibility was blended into PEO to optimize ion migration by solution casting techniques.The mixed electrolyte membrane with 40%PMHS exhibited high ionic conductivity(2.0 x 10-2 S cm-1 at 80°C),large electrochemical window?5.2 V?,high flexibility and thermal stability.When the Li/LiFePO4 battery was assembled,a reversible capacity of approximately 140 mA h g-1?0.1 C?was provided at 60°C.In addition,the battery having the polymer electrolyte exhibits excellent stability.These results indicate that the solidpolymer electrolyte system meets the requirements of the next generation of high energy density all solid state LIBs. |
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